1. Field of the Invention
The present invention relates generally to a fractal antenna for a vehicle, and more particularly, to a fractal antenna for a vehicle in which parasitic elements are disposed in an inner space formed by radiation elements, thereby generating broadband resonance frequencies, two radiation elements are disposed opposite each other on the left and right sides, thereby providing an omnidirectional antenna, and which uses a pattern having a fractal structure, so that space efficiency is improved, thereby reducing the size of the antenna.
2. Description of the Related Art
Generally, micro-strip patch antennas are currently most widely used as antennas used in land broadcasting, satellite broadcasting, and communication. However, such a micro-strip patch antenna has problems in that the efficiency thereof is considerably low, and the active management of bandwidth is difficult because the bandwidth is narrow, so that the center frequency of the bandwidth changes depending on variations in the surrounding environment.
Further, a conventional antenna has been manufactured using a method of printing an antenna pattern on part of a printed circuit board, on which a signal transmission/reception circuit and a data processing circuit are printed. In the case in which an antenna pattern is printed on a printed circuit board and an antenna is integrally provided, radiation patterns are not regular in all directions. Therefore, a problem occurs in that radiation efficiency for a specific direction is low, so that reception sensitivity is decreased. In order to perform mobile communication, such as the reception of Digital Multimedia Broadcasting (DMB) broadcasts and Amplitude Modulation/Frequency Modulation (AM/FM) broadcasts, communication must be performed in all directions, and thus it is considerably important for an antenna to have good omnidirectional characteristics in two dimensions.
In addition, when signals are received having a frequency bandwidth of which the central frequency is 200 MHz, such as DMB signals, the electrical length of a monopole antenna is generally 37.6 cm. The length of an AM/FM broadcasting antenna, which uses a lower frequency band than the DMB broadcasting antenna, is longer than that of the DMB broadcasting antenna. However, an antenna which has been conventionally used and has the appearance of a protruding structure, has problems in that it is undesirable in safety and appearance, it is inconvenient, and may be damaged when a vehicle is washed.
Therefore, a realistic, practical solution, which can reduce the size of an antenna by acquiring the electrical length of a radiation element in a limited space, has good omnidirectional characteristics so as to be suitable to receive DMB and AM/FM broadcasts, and which can realize broadband characteristics by optimizing the performance of the antenna, is seriously required.